


Magic vs Logic: Nightingale meets Sherlock

by ladydoor



Category: Rivers of London - Ben Aaronovitch, Sherlock (TV)
Genre: Alternate Universe, Crossover, First Meeting, Gen, Magic vs Science, Nightinale meets Sherlock, Nightingale is not amused, Rivers of London meet Sherlock, Sherlock Being Sherlock, mostly POV Nightingale, otherwise canon compliant
Language: English
Status: In-Progress
Published: 2017-12-20
Updated: 2017-12-27
Packaged: 2019-02-17 11:59:05
Rating: General Audiences
Warnings: No Archive Warnings Apply
Chapters: 5
Words: 6,495
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/13076409
Author URL: https://archiveofourown.org/users/ladydoor/pseuds/ladydoor
Summary: What would happen if Nightingale met Sherlock? Let's find out...Crossover between Rivers of London and Sherlock (TV).





	1. Chapter 1

Thomas Nightingale wasn’t in his best mood. The last few days were hell to put it mildly and he struggled hard to keep his composure. Two murders in the last three weeks, both bodies had their chests almost shredded by claws of some kind and both evinced the same _vestigia_ : wet fur, hot blood and resin. As if… In any case, investigation had led nowhere so far, digging in the magic library likewise.

When Peter appeared in the doorway of the library to tell him they had another body, he just groaned.

“I’m coming,” Nightingale dismissed him but Peter didn’t move.

“What is it?”

“Err, guv… there is a tiny problem…”

“Spit it out.”

Peter coughed. “They seemed to misjudge the cause of death, sent the body to the different hospital and assigned the local unit to the case.”

“ _Misjudge_? The same modus operandi as the first two? Did they think that there is an overgrown wolf running loose in central London?”

“Or that somebody in Wolverine costume went a bit angry?” offered Peter aiming to lighten the atmosphere.

Nightingale stared blankly at him.

“Nevermind,” Peter said quickly. The depths of his governor's ignorance to pop-cultural references would never cease to amaze him.

“Where did they put the body?”

“St Bartholomew’s and the man in charge is,” Peter checked his notes, “Detective Inspector Greg Lestrade.”

“I believe I haven’t had yet the honour to meet him. Let’s rectify it, shall we?” Nightingale took his cane and followed Peter to the stairs.

\-----

Peter could say just from the way Nightingale was driving that his boss was annoyed. He was sure that hadn’t Nightingale worn the leather gloves, Peter could have seen his white knuckles - so hard he was gripping the wheel.

They entered the hospital and shot straight to the morgue. There were four people in, leaning over the body. ‘Brilliant,’ thought Thomas. ‘That’s exactly what we need right now.’

He identified the pathologist immediately: a small nervous woman in a lab coat. Beside her three men were standing, all in civil clothes.

“Excuse me,” his tone implied that he didn’t care about excuses at all, authority spreading from him in waves. “Which one of you is Detective Inspector Lestrade?”

“That would be me,” said the man with closely shaved grey hair. “And you are?”

“Detective Chief Inspector Thomas Nightingale, Special Assessment Unit.”

Lestrade’s eyes widened. “You mean the Folly?”

“Yes. And I believe there was a mistake and this body is ours. Will you please step back and let us examine it?”

“Sorry,” the tall man in the long dark coat spoke in low timbre, “what is ‘the Folly’?” There was an irritation and impatience almost palpable in his voice. The last man, small with a military haircut, tried to blend with the background, the same way as Peter did when the inspectors started to pull ranks on each other, more precisely when Nightingale pulled rank on poor Lestrade.

Nightingale turned to the tall man. “Who are you and what is your position?”

“Sherlock Holmes, a consulting detective,” he said with the condescending air.

“A civilian?” Nightingale turned back to Lestrade, “you are taking civilians to the morgue?!”

Lestrade visibly shrunk. “We need him…He is helping us with solving cases.”

Nightingale ran his hand over his face. He got the feeling that he had stepped into an especially bad episode of some crime TV show.

“And who is this?” he exasperatedly pointed to the last man. “The cleaning lady?”

“Doctor John Watson,” mumbled the small man.

“A doctor of what exactly?”

“Former army doctor, now a general practitioner.“

“Hm. I think that these,” Nightingale waved his hand towards the boxes, “aren’t exactly in need of your services any more, Doctor. Or am I mistaken?”

The doctor shuffled uncomfortably.

Nightingale turned back to Lestrade: “I will be demanding an official explanation later, Detective Inspector. Right now, however, we are running short of time. Please. Step. Back.”

When they did what they’d been told, Nightingale beckoned to Peter and one after another lowered their faces over the body, stopping only a few inches from its face and searching for any _vestigia_. Nightingale considered it quite redundant - a glance over the wounds told him everything - but they had to be sure.

“What do you think?” Nightingale asked when Peter straightened up.

“It’s the same one and definitely Falcon, Sir,” said Peter, reasonably reluctant to add more in the presence of others.

“Yes, it is. Arrange the transfer to Dr. Walid, Peter, would you? Call me if you need anything,” Nightingale turned around to leave.

“Wait,” called the arrogant voice. “Can somebody explain what is bloody hell going on here?!”

Nightingale turned back to face the consulting detective. He hadn’t had such a strong desire to punch someone in the face for a really long time.

“Don’t you think your attitude is a bit presumptuous if we take into consideration that you shouldn’t have been here in the first place?” He locked his eyes into the Mr. Holmes’s green ones. Or were they blue? Regardless, they were cold, intelligent - and angry.

‘Careful, Thomas, this man could do a lot of damage if he started poking around. He is intelligent and determined enough to not cease asking questions until he gets his answers,’ Nightingale warned himself. On the other hand, if he showed him what was  _bloody_ _hell_ going on here, wouldn’t it blow up his brain? Oh well, he simply had to hope that the young man would deal with it.

“Can you all leave us alone for a minute, please?”

Nightingale closed the glass door after them, the last being the pathologist who had been casting adoring glances at the detective for the whole time. ‘No, not a crime TV show, a romantic crime TV show,’ he internally rolled his eyes.

“Please, turn off your mobile phone and any computers in the vicinity.” When Holmes didn’t move, he added: “Do it or I won’t tell you anything.”

That seemed to work and at last, the detective complied. He turned off his smartphone and also the pathologist’s computer. Nightingale switched his phone off too.

“Usually,” said Nightingale, “we go by ‘the fewer people know about us, the better’ policy, but you are not the one to be fooled easily, are you?”

“No.”

“Right. And at the same time you will not believe to what I’m going to tell you unless I show you. Therefore I request you let me talk without interrupting, however incredible it will seem to you. Understood?”

The detective huffed and rolled his eyes.

Nightingale chuckled. “I take it as an agreement. The Folly, or the Special Assessment Unit is an unit of the Metropolitan Police dealing with magic. Falcon is a code name for everything that falls within our authority.”

Holmes opened his mouth, presumably to tell him that he is barking mad, but Nightingale raised his hand. “No. Talking.”

“It was founded by Sir Isaac Newton,” he continued, “yes, the very one whom you possibly take as the father of modern science. You may even know his book _Philosophiae Naturalis Principia Mathematica_ , but not his other one, _Philosophiae Naturalis Principia Artes Magicis_. The Folly consists of Constable Peter Grant, whom you have met a moment ago, and me. He is an apprentice and I am his Master, as I am probably the most capable wizard in Britain at this moment, in fact until recently it was thought that I am the only one left.”

That was too much for the poor man. He snorted incredulously. “Are you crazy? Or is this some kind of prank John pulled on me?”

“No. I’m sorry I have to do this to your organised brain but you are the one who wanted to know. Mr. Holmes, allow me to introduce madness into your life,” and with those words Nightingale turned off the lights, adjusted his cuffs, and conjured a werelight.

  



	2. Chapter 2

**Summary for the Chapter:**

> Spoiler alert! Everyone has seen all the Sherlock episodes many times already, right? But to be sure: spoilers for S4 ahead in this chapter.  
> \---  
> Few people have had the honour of rendering Sherlock speechless... In my imagination Nightingale is one of them :) And John is BAMF.

The dim yellow light illuminated Holmes’s shocked face, creating deep shadows under his cheekbones.

“How…” he trailed off. “What trick is this? Mirrors? A string attached somewhere? Some kind of device? Laser?”

He moved closer and ran his palm around the globe of light. That didn’t affect it. He narrowed his eyes and tried to touch it.

“It generates heat!”

“It does,” said Nightingale, moved his hand and let the globe float around the room. “No mirrors, not strings, no devices, and no laser.”

He dismissed the globe, turned the lights back on and conjured a waterball.

“Impossible,” exhaled Holmes.

“No. You have just not yet accounted for its possibility.”

“Hypnosis!” The detective tried another theory.

Nightingale stared him down. “You know that it’s quite impossible to hypnotise someone just by looking in their eyes without the cooperation of the subject, don't you? On the other hand, I could put a spell on you with the similar results.”

By the flick of his hand, he sent the waterball into the sink where it burst into thousand droplets.

“I could also show you a fireball, but they tend to be rather forceful, therefore not entirely suitable as an indoor activity.”

The detective sat down on the pathologist’s chair with a heavy _thump_. He opened and closed his mouth but no words came out. Nightingale somehow got the feeling that that was quite a rare occurrence in Holmes’s life. He observed the detective with sympathy. He knew that Holmes wasn't able to absorb any more information at the moment. A blue scarf lying on the pathologist’s table suddenly moved up, and gently wrapped itself around Holmes's neck, as Nightingale slowly moved his fingers. The ends of the scarf tugged the detective up and he obeyed, his disoriented eyes fixed on Nightingale.

“Come on, let me get you a cab. You should probably rest a little. Here,” Nightingale scrambled his phone number and address to the piece of paper and slipped it in Holmes's coat pocket. "Call me whenever you wish."

Holmes, still stunned and speechless, followed him out of the morgue.

\------

Nightingale didn’t have much time to think about Holmes in the next 48 hours. He and Peter cracked the case and hunted the culprit down. When they got back to the Folly, it was about 11 a.m. and they hadn’t slept for two days. They went straight to their respective rooms to get the much deserved rest.

Nightingale had slept for only a few seconds - at least it felt like that - when he woke up with the sense of doom looming over him. He didn’t even open his eyes.

“Molly.” He really wished her to stop doing this. “What happened?”

She handed him a business card.

“We have a visitor?” He reached for the watches lying on the bedside table and found out to his dismay that it was only 2 p.m. Well, so much for the well deserved rest. He tried to focus on the card.

_Dr. John Watson, MD_

He was suddenly very much awake.

“You opened the door for him?”

She gave him a stare which said ‘What was I supposed to do when you two were sleeping like logs?’ Sometimes he wondered how it was possible to express oneself so precisely without saying a single word.

“Where is he now?”

She beckoned her head in the direction of mundane library.

“I’ll be right there.”

He dressed quickly, horrible scenarios running through his head. He sincerely hoped nothing bad had happened to the detective, not merely because he would be responsible for it a little. _Fine_ , a lot. He went to the bathroom and splashed water over his face.

Lately, the number of people who _knew_ had been rising, and after years of near solitude he felt overwhelmed. He had taken Peter as an apprentice with consideration and that was fine, but he wasn’t really ready for dealing with civilians randomly popping up in the Folly. Nor he was ready for apprentices deserting to the enemy side, for that matter. Peter himself had a fascinating ability to attract catastrophes, as Thames Water and TfL would readily testify. And now this. Had Nightingale believed in karma and reincarnation, he would have thought that he had been Jack the Ripper and now he was suffering for that.

Nightingale found Dr. Watson occupying himself with reading the book titles in the library. He turned around. His eyes were worried sick, his clothes wrinkled and face unshaven, and dark circles forming under his eyes revealed lack of sleep.

"Your... err... your maid let me in."

“Doctor.” They shook hands. “What can I do for you?”

“It’s about Sherlock. I found your address in his pocket. I don’t know what you two talked about, but since then he has been in a really weird state. He has been lying on the sofa for two days, completely ignoring me...” He frowned and corrected himself: “Err, that’s quite standard behaviour when he needs to think, but it's the intensity what frightens me. Usually, I’m able to get at least a glass of water into him now and then. Now I even haven’t seen him going to the bathroom. He is so deep in his Mind Palace that I cannot reach him.”

“In his what?”

“He says his mind is formed as a place and his thoughts are organised there. When he needs to remember a particular thing, he sort of shuts himself down there.”

“Oh, the memory theatre technique, I see. Well, Doctor, I’m afraid that what I told him requires the complete rebuilding of the said palace. From the very foundations. It could take considerable time and I don’t suggest interrupting the process. As a doctor, can you possibly put him on drip-feed?”

“Yeah, I can arrange that. Most likely he won’t even notice.”

“Very well. Give him time.” Nightingale was inclined to believe that this mental technique could actually help the detective cope.

Watson cleared his throat: “Inspector?”

“Yes?”

“ _What_ did you tell him?”

Nightingale contemplated for a while. “You are close friends, I gather?”

“He is my best friend. I need to know what’s happening. I need to help him,” the doctor said earnestly.

“Go and take care of him. Find someone who will keep an eye on him and come back in the evening. I’ll show you.”

Watson nodded, said goodbye, and left.

Nightingale sighed, went to the window, and rested his forehead against the cool glass panel. ‘Why don’t we set up a tent in the middle of Trafalgar Square and collect admissions straight away? _Proper real genuine magic, ladies and gentlemen, come and see for yourselves!_ ’

\-----

When Doctor Watson arrived to the Folly that evening, he was much calmer. He had ensured that Sherlock wouldn’t die of thirst and had entrusted him to Mrs. Hudson’s loving care. Nightingale’s mood improved significantly too, once he had actually slept for uninterrupted five hours. He and Peter had some training to catch up on and Nightingale got the idea that he could as well kill two birds with one stone and that it wouldn’t have to be _him_ parading himself with werelights and whatnots this time.

He led Watson through the corridor to the lab.

“I asked Lestrade about you and the only thing I was able to get from him was that you are dealing with weird… stuff.”

“Certainly one way to put it,” Nightingale replied, knowing exactly what word Lestrade had used.

“So… did he mean… UFO?”

“Not yet and hopefully not ever. We have much to do with terrestrial beings alone.”  

“Right… what weird stuff, then?”

Instead of the answer, Nightingale opened the door to the lab. Inside, Peter was just practising _Impello_ combined with _Iactus._ Luckily, neither he nor the room needed the protection against randomly exploding apples any longer. He grew quite proficient and precise with his aim and speed.

The doctor stopped short and his eyebrows moved somewhere above his forehead.

“ _This_ weird stuff,” Nightingale pointed evenly.

“So,” Watson said conversationally, “magic exists. Right. Well… I mean I no longer wonder that talking to you took Sherlock’s brain to pieces. In fact, I feel like sitting down now if you wouldn’t mind.”

Peter pushed the chair towards him and the doctor sat on it carefully.

Nightingale was impressed. “You seem to take it rather well.”

Watson inhaled. “First, I went through Afghanistan. Second, since I have met Sherlock Holmes, I was held hostage, attached to explosives, aimed at by snipers, and drugged by Sherlock himself to have hallucinations of a demonic hound. We broke into a military base to investigate an escaped luminous rabbit. I thought Sherlock was dead for two years while he was busy dismantling the biggest criminal network in Europe. My wife was killed while she was trying to protect him. After a very difficult time we got back together only to find ourselves in a twisted version of _Fort Boyard_ pulled by his insane but deadly genius sister. Do you really think anything could possibly shock me any more, Inspector?”

“Well, life with Sherlock Holmes certainly seems to be an interesting one.”

“You have NO idea.”

“Starting to.”

 


	3. Chapter 3

**Summary for the Chapter:**

> More talking in this chapter, but there is a lot to talk about, so...  
> But there is something actually happening in the next chapter, I swear :-))

Nightingale observed from the window as a cab pulled up in front of the Folly and the great detective stepped out, his well-cut coat flying behind him. Nightingale had received an early-warning call from John Watson, that he had woken up to Sherlock being as good as new and buzzing with energy, and that the detective was currently on his way to the Folly. Relief flooded him and he found himself smiling. He was genuinely happy that Holmes had scraped through, even though he knew that the following interview wouldn’t be easy.

He met him in the foyer.

“Mr. Holmes, I’m glad to see you safe and sound,” he stretched his hand.

The detective shook it. “Call me Sherlock, please.”

Nightingale nodded but didn’t reciprocate. Only a few people called Nightingale by his first name. He was quite comfortable with ‘Nightingale’ or ‘Inspector’ or ‘guv’ as Peter called him.

Once they were seated in armchairs by the fireplace, Nightingale grew serious: “I hope I don’t have to say that all of this is confidential.”

Sherlock snorted. “Believe me, I don’t have any intention to spend the rest of my life in a madhouse. But I’m glad I can talk to John about it. It would drive me crazy to hide that from him.” His eyes clouded and his arrogant stance faltered but he instantly recovered.

He rested his elbows on the armrests, put the hands together and propped his chin on the fingertips.

“Right. I have rebuilt my mind to accommodate for the new possibilities, but I don’t know what they are. I need to know everything.”

It wasn’t lost on Nightingale that Sherlock hadn’t mentioned learning actual magic. It was all about knowing, not doing. He felt relieved because he really didn’t dare to imagine what would mean to empower this genius - whose personal vocabulary apparently didn’t contain words like restraint or self-preservation instinct - with magic. He would have loved to leave it at that, but he had heard enough about Sherlock’s self-destructive inclinations. He had to be sure that the detective wouldn’t try to puzzle out the art of magic on his own.

“You don’t want to-?”

“To become an apprentice? No.” Sherlock must have seen that Nightingale was taken aback, so he added: “I’m a consulting detective, Inspector. I invented the job, I’m great at it, and I love it. This is what drives me, this is who I _am_. I need to know these new facts to account for them in the case-solving process. I don’t need to be able to fly around on the broomstick - I just need to know whether it can be done.”

“You have been watching Harry Potter too much,” Nightingale commented drily on the broomstick example. “Fine. But promise me that in case you change your mind for whatever reason, you will let me know. I mean it, Sherlock, it’s dangerous to perform magic without supervision. I’ll send you to our pathologist, he will show you some MRI scans of the unfortunate people who had first-hand experience.”

The detective rolled his eyes at the lecture, but nodded.

They spent the morning immersed in conversation. Sherlock had many questions, Nightingale tried to answer them as well as he could. When he mentioned the after-war period, Sherlock narrowed his eyes.

“How old are you?”

“What do you think?” Nightingale leaned back, hands on the armrests, subjecting himself to Sherlock’s observant eyes.

“Of course, I have been stupid, stupid! I _did_ notice when I first saw you; something was off and it was nagging me but...,” Sherlock pursed his lips, clearly irritated with himself.

“Everything of you is shifted back in time. Your clothes and shoes most obviously: old fashioned, but expensive, bespoke, well matched, carefully tended. You aren’t exactly a vain person, though, therefore it must have been ingrained in you in the era when this had been an expected standard. The same goes for your manners, even the way you hold yourself. Your vocabulary betrays that too, although you have acquired some modern phrases from your apprentice. If the Jag parking in front of the Folly is yours, it’s a Mark 2 model, which was produced in the sixties. The car is in great condition, it was either bought brand new right then or later from a collector but I somehow,” Sherlock exhaled, “bet on the first option.”

Nightingale raised the eyebrow. “I begin to see why Lestrade needs you. I may be inclined to forgive him.”

Sherlock continued as if he hadn’t heard, but a tiny self-satisfied smirk betrayed him.

“So, judging that you had to be well-off to be able to buy such a car, I would say that you had to be in at least your forties or fifties then. My educated guess of your age is around one hundred.”

“Very close. Add about fifteen years,” said Nightingale.

Sherlock whistled.

\-----

Nightingale agreed that Sherlock, being well versed in Latin, could come and read some books Nightingale would select for him. Over the following weeks, Sherlock’s presence in the Folly gradually became commonplace. He would pop up there randomly between his cases, research a bit or chat with Peter or Nightingale. He also become acquainted with Dr. Walid and, together with John and Dr. Vaughan, spent a few lovely afternoons over the HTD brain slices. Delighted Abdul promised him that he would call him for the future experiments.

John visited the Folly too, teaching Peter hand-to-hand combat tactics and also advanced first-aid, with Nightingale’s pleased approval. Molly seemed to tolerate both men just fine; however, the same couldn’t be said of them. Hair on the back of Sherlock's neck rised every time she glided around and John jumped into the full defensive mode when she appeared noiselessly behind his back. But they both appreciated her culinary talent - even her experiments, which neither Nightingale nor Peter could comprehend - and often stayed for dinner.

It was after one of these dinners that Peter brought up a peculiar incident which had been handed over to SAU due to its similarity with one of their latest cases.

“Maybe Sherlock could take a look and deduce a thing or two of it, Sir?”

Nightingale decided that he definitely owed Lestrade an apology now, but reluctantly agreed.

Peter produced a piece of paper in the plastic evidence bag and handed it over to Sherlock.

**Notes for the Chapter:**

> Sherlock is quite reasonable, isn't he? But we have not seen the end of it yet.


	4. Chapter 4

**Summary for the Chapter:**

> Spoiler alert: spoiler for The Furthest Station ahead - just minor one from the beginning of the book, but it's there.

Sherlock took out a pocket magnifier and carefully examined the slip of paper. There was only one word written on it: Angel. 

“How did you get it?”

“I will tell you later. Can you deduce anything just from the note itself?” 

“Sure. It’s written with the fountain pen, the ink shade is probably Diamine Woodland Green, but I can’t be a hundred per cent sure in this artificial light. The line is made by a medium width nib even if the handwriting is small - a fine or extra fine nib would have been more suitable. The medium nib is however best for the true shade of the ink to show - anything narrower and it would darken. From that I can gather that someone cared very much about the ink - but not about the paper. Look,” he turned the paper over. 

“It is cheap generic paper with low grammage. It completely bleeds through. Do you see these fibres?” He showed them how the writing blurred on its sides into tiny traces, making the lines look fuzzy. “It is not a paper anyone regularly writing with fountain pens would choose. The handwriting is definitely female, she is small, tidy, and modest. I would need more than a single word for in-depth analysis, though.” 

“That would add weight to my theory,” said Peter, “that the woman who clutched it had written it.” 

“So, what happened?”

Peter took the floor: “Yesterday evening, a scared woman ran into the constable patrolling around Smithfield Market. She was holding this paper and she was almost out of her mind. After a few minutes she calmed down and started to act as if nothing had happened. The constable was so confused that he didn’t take any personal details and let her go. He reported it later, though, and marked it as Falcon related.” 

“Which was fortunate,” Nightingale added, “because we have recently encountered a similar phenomenon. People reporting some kind of abuse and within a few minutes forgetting what happened. The abusers were ghosts and it seems that the memories of their presence are prone to vanishing very quickly.” He briefly summarized the case.

“What makes you think she wrote the note?” asked John.

“The things ghosts create disappear with them.” 

“So she was-” there was reluctance in John’s voice to pronounce it, “possessed?”

“Probably,” said Nightingale, and a shadow crossed his face. “We have personally witnessed the possibility, haven’t we, Peter?”

“Yes, guv,” Peter shivered. He didn’t like the memories of it at all. 

Sherlock began to pace the room, not listening to them any more, fingers tapping on his lips. 

“There is no meaning to it yet,” said Nightingale. “I suppose we have to wait for more clues.” 

Sherlock abruptly stopped. 

“But Angel is an…”

He turned on his heel and dashed out of the room with the paper still in his hand.

“He does this often I gather?” Nightingale asked John.

“Yeah.”

Nightingale didn’t waste any more time, murmured something under his breath and snapped his fingers. There was a loud  _ thud  _ coming from the foyer, followed by a very surprised “Ow!”

Nightingale chuckled humourlessly. “Well, not on my watch.”

Peter glanced at him, astonished: “You have erected a shield against him!”

“A slowly moving shield, to be precise. He will soon find out that he has no other option than to come back. Or to be pushed back, depending how reasonable he decides to be.”

In a minute, the detective was standing in the doorway, seething. His hand was pressing his forehead.

“That wasn’t fair!”

Nightingale’s steel-grey eyes gave Sherlock a cold stare.

“Lestrade may be helpless against your excesses but I am not. A bump on your forehead is nowhere near the worst I can do to you. Now listen, Sherlock, and listen good because I won’t repeat myself. One apprentice with a talent for getting himself in trouble is quite enough. I won’t have another madman running around our cases. Peter here was many times in danger of his life, and he either saved himself by quick-witted use of magic, or somebody else came to his rescue just because we knew where he was!”

Peter grunted silently at “another madman”, but the following praise of his wits appeased him. John murmured something that was very close to “Praise the Lord”.

Nightingale continued: “We all know you are clever, you don’t have to prove yourself. But when it comes to your knowledge of magic and its danger, you are still very much out of your depth. To be able to save your arse, I have to know where you are at any given time. Either you will acknowledge my authority, or you will not be allowed to participate. Is that understood?” 

The fight between Sherlock’s pride and passion for puzzle solving was visible in his face. He was breathing hard. John and Peter tensed. Nightingale waited patiently.

“Yes.”

“Yes what?”

“Yes, I will acknowledge your authority,” Sherlock gritted through his teeth.

“Very well. Where are we going?”

“The Angel Underground station.”

\-----

Fortunately, Angel was a station serving only one line, Northern. It had two platforms and one entrance on the spot where Upper Street met Islington High Street. The old entrance around the corner had been closed after the refurbishment in 1990s. They searched the station but found nothing suspicious, visible or invisible. Toby wasn’t impressed either and eyed them accusingly for dragging him out of his warm spot in the kitchen for nothing.

Sherlock looked distressed and his frown created deep horizontal wrinkles between his eyebrows.

“What’s wrong?” John asked, apparently knowing this look very well.

“I don’t know why we are here.”

“What do you mean?”

“It just occurred to me that Angel is an Underground station, but there isn’t any train of thought behind it.”

John snorted, looking at the tracks. “Pun intended?”

Sherlock rolled his eyes. “Oh, stop it!” 

Peter stepped in. “Maybe it’s because we talked about the Metropolitan Line case just before?”

Sherlock spun around. “That’s not how my brain works,” he hissed. “Look, Angel could mean millions of other things. I always have a reason for what I’m doing, this time it just randomly popped up in my head and I don’t know why. I don’t even remember anything in particular about this station apart from its existence.” 

He was eyeing the platform up and down in obvious frustration.

“It was worth a try,” said Nightingale conciliatorily. “Let’s go home. Peter, monitor the database and alert all the constables to the need to report similar incidents. Search for past incidents at Smithfield Market and at this station as well. Sherlock, keep the eyes of your informant network open. We will report to each other if something emerges.”  

“Yes, guv,” said Peter, who was searching Wikipedia in the meantime. “Nothing relevant it seems… Did you know that Angel has the longest escalator on the Underground network and that this platform is unusually broad because there were two tunnels before, not one?” 

Sherlock’s head twitched but he didn’t say anything.

**Notes for the Chapter:**

> I love Sherlock but I just couldn't resist doing this to him. Seems that I'm #teamnightingale after all. Sherlock literally didn't see it coming :-)


	5. Chapter 5

**Summary for the Chapter:**

> Spoiler alert: a minor spoiler for The Furthest Station again. But maybe it was mentioned in the previous books also, I'm not sure.

When Nightingale called Sherlock two days later, he answered immediately and didn’t waste time on niceties. 

“Where?”

“In the street near the Barbican Centre. A man, similarly distressed. This time, the constable got the details, but the check revealed nothing. Same ink, different paper and different handwriting. It appears you were right, the ink is important.”

“Yes. And it is really Diamine Woodland Green, I have checked. What does the note say?”

“Wembley Park.” Nightingale heard Sherlock breathe in sharply but continued. “Yes, that’s an Underground station, besides the other things. We are going to search it, do you want to come along?”

“Is the Pope Catholic?”

\-----

“This is getting ridiculous,” said John when they had searched through all the platforms of the Wembley Park station and found - nothing.

“Are all your cases so dull?” Sherlock snapped at Nightingale. 

Nightingale silently recapitulated all the horrible things he and Peter had seen in the last few years and replied simply: “No.”

“Well, then I’m apparently in bad luck. Anything interesting?” Sherlock turned to Peter who was scrolling on the phone.

“Let me see. Well, there was an amusement park even prior to the stadium. The then chairman of Metropolitan Railway wanted to build a copy of the Eiffel Tower there. The project went belly up, though, only a part of the tower was built and it was later demolished. It was called,” Peter paused and looked at Nightingale, “Watkin’s Folly?”

Nightingale gave it a thought. “It has nothing to do with the Folly. As far as I know.”

Some emotion flashed through Sherlock’s eyes but it was gone in an instant. The detective shook his head.

“Do you think it is meant to tell us something?” John asked, scratching his head.

“Yes. That we are fools and that we are wasting our time here,” Sherlock growled. 

\----- 

The third message was caught in the late afternoon a few days later not by the police, but retrieved from the litter bin by one of Sherlock’s informants. The busker saw an utterly confused woman stumbling near the St Paul’s Cathedral. She stared at the paper in her hands and then tossed it into the bin. He took it and, seeing that the note “Piccadilly Circus” is written in green ink, delivered it to Baker Street. 

All four men met at the Piccadilly. It was crowded and so was the Underground station. They went in and stopped in the circular entrance hall. Confused tourists were everywhere, searching for the right exit. 

“What’s that?” Sherlock pointed at the sign on the wall. There was the typical Underground roundel, but instead of the station name there was Frank Pick written on the blue bar. Next to the roundel there were eight words: Beauty, Immortality, Utility, Perfection, Goodness, Righteousness, Truth, and Wisdom.

This time, Peter didn’t need the Wikipedia. 

“It’s a monument of Frank Pick. He put together the Underground as we know it. He commissioned the most beautiful station buildings, for example Arnos Grove.” 

Nightingale smiled faintly, as Peter’s architectonic nerdiness showed again.

Sherlock frowned, took up his phone and started furiously typing. In a second, he stared at the screen in disbelief.

“Frank Pick... used green ink for his memoranda.”

John whistled: “A clue, at least? You think all of this is the doing of Frank Pick’s ghost?”

“It’s a possibility,” Nightingale considered.

Peter coughed. “Sorry to spoil the mood, but he died in his house in Golders Green.”

“So what?” Sherlock asked.

“It’s too far. Ghosts are attached to the  _ vestigia _ of the places where they died. Unless they are caught in a trap.”

“Nevermind. The more important question is: how did I know I should google that?”

\-----

They were back at Russell Square, munching at scones and tea which Molly prepared for them. Sherlock frantically paced the room. John sat in the armchair and observed him. It was obvious that the detective knew more that he had given out.

“I am the last person who would complain that we haven’t found anything horrible, yet… This doesn’t make any sense, except we are all getting quite proficient in Underground trivia,” said Nightingale, leaning back in the armchair with a sigh.

John jumped up: “Underground trivia! Sherlock… do you remember the book I gave you after our Underground case?”

“What book?”

“Right, that’s what I thought. Listen. After we had cracked the case, we joked that it was the first and last time when you had set foot on the Underground. I gave you a book full of miscellaneous Underground facts, just for fun of it. You tossed it somewhere in the flat. What happened to it? Think!” 

Sherlock’s eyes grew distant. John grabbed Sherlock’s shoulders and shook him. 

“No no no, not your Mind Palace. It’s not there, otherwise you would have remembered it. Think as the ordinary human being.”

“As a what?!”

“Sherlock!”

Sherlock shut his eyes tight and pressed the fingers on his temples. The concentration was so intense that it looked like his head was going to explode.

Nightingale watched him carefully.

After a few minutes, Sherlock opened his eyes: “I need a map of London.”

Peter fetched one from the mundane library and folded it out on the table.

“You said that ghosts are attached to the  _ vestigia  _ of places where they died. The stations we visited are just tossed around. But do you see this triangle?” Sherlock tapped his fingers on the map. 

“Here is Barbican, here is St Paul’s, and here is Smithfield Market. While we have been running like idiots around the Underground stations, it all points here,” he stabbed the index finger into the centre of the triangle. “We should have looked at the source of the notes, not followed clues which weren’t clues at all.”

“The Underground stations are just distractions then?” 

“Yes, but not only - I would call it teasing. You are familiar with the feeling that you have something on the tip of your tongue but you cannot get to it, aren’t you? To me, this happens very rarely, but since the first message I have had this itching almost constantly. It has been maddening me. I  _ did  _ read the book John gave me. About half a year ago, I was going to the lab to work on an experiment. I knew it would require my constant presence but not complete attention, so I grabbed this book just to have something to kill the time with. I was so bored! I flipped through the pages, then tossed the book in the lab. I didn’t store the information because I didn’t considered it useful. It went just to my short-term memory, and I didn’t bother to delete it. So I forgot about it just like ordinary people do.  _ That  _ was a mistake. God, how can you live like that? Constantly forgetting something but not completely, so it keeps nagging you?”

Nightingale wisely choose to ignore the questions.

“What is this about?”

“It’s a game! And it’s targeted at me, someone must have been in my head, Inspector, don’t you see?” Sherlock grabbed his coat. “Come!”

“Where?”

“You said that you can make ghosts visible by feeding them magic, didn’t you? Well, it’s time to get your spells ready.”

\-----

“Where are we heading?”

“The roof,” Sherlock called the elevator and quickly added: “It’s the only place here void both of people and electronics.”

“That’s true. You certainly don’t wish to cast anything near to the ER or operating rooms. But you will both stay close to the door, under no circumstances you will go near the edge, and you will let me and Peter deal with it, since we don’t know what we are facing, alright?”

Sherlock nodded with an excited gleam in his eyes. John had been rigidly silent since they left the Folly.

It was windy on the rooftop, and the sky was almost dark. Sherlock’s coat flapped behind him as he stood in intense concentration. Nightingale and Peter positioned themselves a bit on the sides to get more manoeuvring space. Nightingale conjured a very pale werelight, sent it in the middle of the roof and gradually added strength to the spell. 

As the figure started to materialize, the first visible thing was the legs against the light grey low wall on the shorter side of the roof. Then they identified the rest of the silhouette sitting there: the black coat almost blending with dark sky, the head lazily cocked to the side, lips twisted in an amused grin.

“Did you miss me?”

  
  


**Notes for the Chapter:**

> Seems I caught the Moffat-Gatiss disease and simply had to bring him back :) 
> 
> I'm seriously tempted to leave it at that. But I have the following scene in my head and it is kind of interesting... Oh well. Let me know what you think :)

**Author's Note:**

> Thanks for reading this! Let me know whether you enjoyed it. Also, please report any mistakes, I'm not a native speaker and I will be grateful :)
> 
> I finally decided on the time frame. The work is set after SH The Final Problem and after RoL The Furthest Station and The Hanging Tree. I guess that I won't need a lot of specific mentions and when I will, there will be spoiler alerts at the beginning of the respective chapters.


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